Pulverizer mill



March 18, 1930. R o, @ROMAN 1,750,636

PULVERI ZER MILL Filed Feb. 11. 1927 ATTORN EYJ Patented vlidar. {8,11930 UNITED STATES PATENT OFFICE RUSSELL ORLANDO GRDMAN, OFCATASAUQUA, PENNSYLVANIA, ASSIGNOR TO FULLER- LEHIGH COMPANY, OF FULLERTON, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA.

PULVERIZER MILL Application led February l1, 1,927. Serial `Nu.. 167,421.

This invention relates to pulverizer mills, and more particularly to millsof the air sepan "ration type in which the ground material is discharged from the grinding zone by a current of air. The invention is concerned specifically with improvements in 'the manner of' introducing and distributing the air used for separating purposes, and also of-controlling the point atwhch the airis introduced, whereby it is possible to regulate the ineness to which the material is ground.

The mill of the present invention mayv include pulverizing means of Vdifferent types, but I prefer to employ the elements illustrated and disclosed in the patent to Collins, No. 1,484,298, issued February 19, 1924. In the Collins mill the grinding operation is carried on by means of a horizontal grinding ring and grinding balls which are propelled around this ring 'by appropriate pushingdevices. The material is crushed between the balls and the ring, and lifting blades are used which are disposed above the balls and rotate with the latter, these blades causing the finematerial to befthrown upwardly into the mill casing above the grinding zone. In the Collins mill the air which is used for separation purposes is introduced into the casing through a wind box andl a port section which is placed -adjacent to the grinding zone, and extends around the casing, the air'with the fine materialeing then discharged through a -conduit w ich leads from the top ofthe -mill'casing to the usual cyclone separator. I have found that this method of air-separation, and various others of the prior'art with which I am familiar, have the disadvantage'that the pressure and the grinding u consequence that the material discharged from the mill isfnot of uniform fineness, and

, thus the capacity of the mill to grind material to a selected 'size is considerably reduced.

The object ofthe presentl invention is to' f provide means for introducingl air for separationpur oses into the mill in such a way that the lair is evenly distributed at uniform pressure around the inside of themill casing, and particularly in the plane of the grinding zone, so that the ground material is acted on distribution of the air around zone is not uniform, with theby a uniform lifting current and thus remains in the pulverizing zone until reduced to substantially uniform size'. The invention is also directed to the provision of means for controlling the action of the air used for separation purposes, so that the degree of neness to which the material 'is reduced before it is discharged can be regulated as desired.

In order to accomplish the .desired result the new mill includes pulverizing apparatus which operates in a horizontal plae within a casing. Above the pulverizing zone air is introduced for separation purposes into the casing, preferably at the axis of the pulverizing zone and in 'a downward direction. he air and fine material are removed from the casing at the top thereof in an upward direction and led to the usual separator. The air inlet and outlet ducts are preferably arranged concentric, with the outletduct surrounding the inlet duct, so that the air flows through the casing from the inlet duct to the outlet duct to flow outwardly along radial paths. A baille is also provided to cause theI air to flow along the casing wall prior to its entrance into the outlet duct. The end ofthe 'inlet duct lies -withinl the casing at a pointnormally conend section which may be raisedorl lowered with reference to the pulverizingaone, and

whenthis section islin its lowermost position,`

the incoming air current is discharged close to the pulverizing zone, so that it has a greater lifting effectand consequentlyithe material being ground will be discharged more rapidly and thgsf'will be of coarser size. Whenv he Vsection'is placed in its uppermost osition, the material discharged from the mi l will be as line as the grinding ap aratusis capable of producing. In interrne iate positions the size of the material beingI ,discharged will vary in accordance with the position of the section, an dwill become coarser as the section is lowered.

For a better understanding of the invention, reference may be had to the\accompany ing` drawings, `vin which ig. l is a view inside elevation and partly in section, showing the improved mill construction, and

Fig. 2 is a top planview thereof.

Referring now to the drawings, the mill is illustrated as mounted on a suitable bed 20 of concrete or otlier'like material, and it includes a base section 2l to thebottom' of which is connected the casing 22 for the driving mechanism'. In this casing is the lower bearing 23 for the vertical shaft 24 and also abearing 25 for the drive shaft 2,6. The drive' shaft 26 is coupled to the shaft 27 of a driving motor 28 mounted at. any convenient point. rllhe shaft 26 is supported in a. bearing 29 of any suitable construction and carries a beveled gear 30, meshing with a similar gear 3l on the vertical shaft 24. The vertical shaft carries at its upper end a yoke 32 provided with ushing-devices, not illustrated, for propelling the balls'33 which, in the operation of the mill, run in the grooved face of a grinding ring 34 mounted in the section 21. The yoke 32 carries' lifting blades 35 of suitable form, these blades being inclined so as to cause the material being ground to be raised from the grinding zone-as the yoke is rotated. The details of the pulverizing and lifting apparatus may vary within wide limits and as these parts are well-known in the art, a detailed description of them is not necessary.

Above the base section 21 is mounted a casing section 36 carrying a casing 37 pro vided with a feeder extension 38 through which the material .to be ground ma be introduced into the pulverizing zone.. he casing terminates at its upper end in a neck 39 in which is mounted an outlet duct 40 leading into an airseparator 42 `of any convenient form, here illustrated as being. of the wellknown cyclone type and having a lower discharge end 42 for the material.

l outlet pipe has a section 43 which projects into the casing below the neck 39 and lies clear of the walls of the casing.

A duct 44 serving'as the outlet for air from the separator, leads the air back into the mill casing, the ducty 44 having a portion which enters the wall of the outlet duct 40 and terminates in an end section 45 which projectsv into the casing beyond the end 43 of theoutlet duct. The inlet and outlet ducts are concentric and the inlet duct is also substantially concentric with the shaft 24, .that is, with the axis of the rotating pulverizing elements.

The air discharged from the lower end of the inlet duct into the mill casing passes down into the pulverizing zone and flows.

across the zone alon radial paths to the outer wall of the casing,l eing there deflected upwardly along that wall, as indicated by the The air ient manner, is a fixed baffle 47 -in the form of an inverted, truncated cone. This bale surrounds the lower end 45 of the air inlet duct, and is spaced from it. Owing to the shape and position of the baiiie, the air flowing upwardly along the outer casing wall and carrying with it the fine material passes over the top outer edge of the baille, then turns downwardly slightly, and finally again turns upwardly to liow into the duct to the air separator. In this change of direction the heavier particles carried by the air are precipitated and may fall on the inner surface of the baile, escaping from the lower end ofthe latter, the edge of the baiile at this end being spa-ced from the end of the inlet duct. The manner of introducing the air into the pulverizingzone at the axis thereof and withdrawing it as described results in an even distribution of the air throughout the entire mill casing, and the air pressure within the casing is also uniform. Thus all the particles which are being ground are acted on by air of uniform pressure and velocity, and consequentlythe particles which are lifted by the current are all of substantially the same size.

In order to control the lifting effect of the air, the end section 45 of'the inlet duct is mounted for vertical adjustment, being carried on rods 48 which extend radially fromthe section and are then turned upwardly at right angles and pass through adjusting devices 49 in the wall of the casing. By moving the section 45 upwardly or downwardly, coarse or line particles may be discharged 4from the mill. llVhen the section is in its lowermost position of adjustment, the air current is introduced into the casing at a point close to the pulveiizing zone, and thus yexercises a great lifting effect, capable of causingthe removal of coarse particles from the zone. 4When the sectipn is in its uppermost position of adjustment, the air is discharged into the casing at a point considerably above the zone, and thus more of the air has an opportunity to pass across the casing to its outer walls without entering the zone. The air current under these conditions has aless-lifting effect and the section is so constructed that in its uppermost position the material which is discharged is as fine as the mill is capable of roducing. ment of the end section of the air inlet duct to intermediate positions,.the size ofthe particles which are discharged from the mill may las By adj ustbe varied, but with any position of adjusti ity ,of the ground product which is dis-- barged, due to the more even distribution of 1e air current. Furthermore, the new mill n ing at its opposite end'for introducing air into the casing above the elements and in a downward direction, an air outlet duct at the said end of the casing surrounding and concentric with the air inlet duct for the outward flow of air/from the casing in an upward direction, a baie of inverted truncated form mounted Within the casing in the path of air lowing into the outlet duct and causing the l air to ow along the casing wall prior to its entrance into vthe said outlet duct, and a vertically adjustable end section for the air inlet duct movable to dillerent positions of a'djustment with reference to the elements to vary the point at which air'is admitted into the casing, this end section being movable through the baiile.

2. In a pulverizer mill which includes a power driven pulverizer unit, the combination of a closed 'stationary casing` disposed above and open to the unit, this casing forming an integral part of the mill, an air inlet 'duct entering the casing wall at a point remote from the unit for delivering air into the casing above the unit, and an air outlet duct entering the casing wall adjacent said air inlet ducts and permitting the flow of air from the casing, those portions'orthe ducts Within the casing being concentric and so arranged that the flow of air from the inlet duct to the outlet duct within the casing is partly alonghorizontal, radial paths.

3. In a pulverizer mill which includes a power driven pulverizer unit, the combination of a stationary closed casing disposed above and open to the unit, this casing forming an integral part oi' the mill, an air inlet duct entering the wall of the casing for deliverin g air into the casing above the unit and in a downward direction toward said uni, and an air outlet d`uct entering the casing 'wa l to permit the flow of air from the casing in an upward direction, the portions of these ducts within the casing being concentric and so arrangedthat the lowof air through the casing between the inlet and outlet ducts is partly along horiZontaLiadial paths.

In a pulverizer mill which includes a power driven pulverizer unit, the combination of a closed casing above and in communication with the unit'and forming an integral part of the mill, an air inlet duct entering the casing wall at a point remote from the unit for delivering air into the casing above the unit, an air outlet duct enteri-ng the casing wall and permitting the flow of air from the casing, those parts of the ducts within the casing beingconcentric, and balile meanswithin the casing for causing the air flowing between the inlet and outlet 'duct openings to flow along the outer wall of the casing before it enters the outlet duct.

5. lIn a pulverizer mill which includes a power driven pulverizer unit, the combination of a closed stationary casing forming an integral part of the mill and disposed above n and open to the unit, and air inlet duct entering the casing wall at a point remote from the unit for delivering air into the casing above the unit and in a downward direction toward it, and an air outlet duct entering the casing wall and permitting the low of air from the casing in an upward direction, the portions of the ducts within the casing being concentric with the outletv'duct surrounding the inlet duct, the axis 'of the inlet I duct being co-incident with the axis of the pulverizer unit.

6. In a pulverizer mill which includes a power driven pulverizer unit, the combination of a casing forming an integral part of the mill and disposed above and o en to the unit, an air inlet duct entering t e casing wall for delivering air into the casing above the unit and ina downward direction toward it, this inlet duct having an adjustable en'd section within the casing by means of which the point of delivery of the air into the casing with reference to the unit may be varied, and an air outlet duct entering the casing wall or the upward and outward flow of air from the casing, the pgrtions of the ducts within the casing beingconcentric. l

7 In a pulverizer mill which includes a power-driven pulyerizer unit, the combination ofa stationary closed casing forming an integral part of the mill and lying above and operrto the unit, an inlet duct entering the casing wall for deliverin air into the casing above the unitiand in a downward direction toward it, this duct having an adjustable end section by which thek point of delivery of the air into the casing mayl be varied, and an air outlet duct entering t e casing wall for the upward and outward'flow of air from the casing, the portions of these ducts within the casing being yconcentric and the end sections lof the inlet duct normally lying below the end of the outlet duct; e, v

' 8. -In a pulverizer mill which includes power-driven rotary pulverizerelements, the combination of a closed casing formingl an integral part of the mill and lying above said elements, an airv inlet duct'entending` downwardly through the top wall of the casing Jfor l delivering air above the pulverizer elements, this duct being disposed with its axis coincident with' the axis of the elements, an air outlet duct entering the casing wall, the portions of these ducts within the casing being 'concentric, and battle means in iront of the opening to the air outlet duct arranged to cause the air to flow upwardly along the casing wall prior to its entrance into ,the outlet duct.

9. In a pulverizer mill. which includes power-driven pulverizer elements, the combination of a closed casing disposed above and open to said elements, this casing formin an integral4 part of the mill, an air inlet uct entering the casing wall for delivering air into the casing above the pulverizer elements, this duct having an end section capable o adjustment to vary the point of deliver of the air into the casing, an air outlet uct entering the casing wall for theilow of air from the casing and arranged concentric with the inlet 'ductfand baille means in the path of the air entering the outlet duct and causing the low of airA along the walls of the casing prior to its entrance into the outlet duct. v

10. In a pulverizer miil which includes owerdriven pulverizer elements, the comination of a closed casing forming an'integral part of the mill and lying above the elements and open thereto, an air inlet duct extending downwardly through the top wall of the casing for delivering air above the pulverizer elements, this duct being disposed with its axis coincident with the axis of the elements, an air outlet duct entering the casing wall and surrounding the inlet duct and concentric therewith, an adjustable end section for the inlet duct capable of vertical adjustment to vary the point of delivery or" the air into the Casin@r with reference to the pulverizer elements, and a baie disposed within the casing in the path of the air flowing into the outlet duct, the inlet duct and the baffle cooperating to cause the air to ow across the casing in radial paths, then u wardly along the casing walls to the air out et.

1l. In a pulverizer mill which includes a power-driven pulverizer unit,` the combinan tion of a closed casing disposed above and open to the unit, this casing forming an integral part of the mill, a single air inlet duct entering the casing wall for admitting air into the casing in a downward direction above the unit and in an extension of the axis thereof, an air outletI duct for the i'iow of air from the casing, this outlet duct being concentric with the inletduct, and the ducts cooperating so that air introduced into the casing flows into the unit-and across the latter along radial paths, then upwardly along the casing walltothe outlet.

l2. In la pulverizer miii which includes rotary pilverizer elements operating in .a horizontal plane, the combination of a cas- 1 1 L* mg above and open to sais elements, :.-nis casing being closed and forming an integral part nueces Y of the mill, an air inlet duct entering the casing wall for delivering air into the casing in a downward direction along the axis of the elements, an air outlet duct entering the casing Wall and surrounding and concentric with the inlet duct for the iow of air outwardly from the casing in an upward direction, an end section for the air inlet duct mounted for vertical adjustment whereby the point of admission of the air into the casing may be varied with reference to the plane of the'puL' verizer elements, and baflie means in the casing in the path of the airentering the outlet duct, -the'end section and thebalile means cooperating to cause the air to ow downward into the pulverizing zone, across the latter in radial paths, then upwardly along the casing wall to the outlet duct. e

13. In a pulverizer mill which includesra pulverizer unit, the combination of aclosed casing disposed above and open to the unit, this casing forming an integral part 01"' the mill, an air inlet duct entering the casing wall for introducing the air into the casing above the unit, an air outlet duct entering the casing-wall with its portion within the casing concentric with the inlet duct for the outward iow of air` from the casing, a separator remote from the mill and connected to the eutlet duct, an outlet from the separator connected to the air inlet duct, and a power-driven fan for causing the continuous circulation of air through the casing and the separator.. In testimony whereof I affix my signature.

RUSSELL ORLANB GROMAN. 

